Networking

Nginx status code 444 silently drops a connection without sending any HTTP response to the client. Learn when and how to use it for security and traffic management.

A quick iptables one-liner to reject TCP traffic from a specific source IP with a TCP reset, tagged with a human-readable comment for future reference.

A visual walkthrough of the core networking components that make up an Amazon VPC, from subnets and gateways to security groups and route tables. Understanding how these pieces interact is essential for designing secure, well-segmented cloud networks.

A valid PTR record must resolve to a name that resolves back to the original address. Multiple PTR records for a single address break name resolution and can cause Kerberos ticket verification to fail.

Multiple CNs in a certificate Subject field are deprecated and cause compatibility failures. The SAN extension is the correct way to cover multiple names on a single certificate.

A practical troubleshooting guide for the Kerberos AP REP decryption error, covering the most common causes from keytab mismatches to encryption type misconfigurations.